=== modified file 'Mailman/Handlers/CookHeaders.py'
--- Mailman/Handlers/CookHeaders.py	2016-03-02 09:57:16 +0000
+++ Mailman/Handlers/CookHeaders.py	2016-11-20 06:09:11 +0000
@@ -154,11 +154,26 @@
                 realname = email
         # Remove domain from realname if it looks like an email address
         realname = re.sub(r'@([^ .]+\.)+[^ .]+$', '---', realname)
-        # RFC 2047 encode realname if necessary.
-        realname = str(uheader(mlist, realname))
+        realname, mcset = ch_oneline(realname)
+        sender = msgdata.get('original_sender', msg.get_sender())
+        lang = msgdata.get('lang', mlist.getMemberLanguage(sender))
+        cset = Utils.GetCharSet(lang)
         lrn = mlist.real_name
+        try:
+            if mcset != cset:
+                realname = realname.decode(mcset).encode(cset)
+                mcset = cset
+            lrn = mlist.real_name
+            repl_realname = _('%(realname)s via %(lrn)s')
+        except UnicodeError:
+            syslog('error', 'list: %s: fail to convert "%s" as %s',
+               mlist.internal_name(), realname, cset)
+            repl_realname = '%s via %s' % (realname, lrn)
+        # it may be mcset != Utils.GetCharset(mlist.preferred_language)
+        # so we cannot use uheader() here....
+        repl_realname = str(Header(repl_realname, mcset, None, None, ' '))
         change_header('From',
-                      formataddr((_('%(realname)s via %(lrn)s'),
+                      formataddr((repl_realname,
                                  mlist.GetListEmail())),
                       mlist, msg, msgdata)
     else:
@@ -401,7 +416,10 @@
     # subject: [subject prefix]
     if subject.strip() == '':
         subject = _('(no subject)')
-        cset = Utils.GetCharSet(mlist.preferred_language)
+        # subject is now sender's preferred language, not list's.
+        sender = msgdata.get('original_sender', msg.get_sender())
+        lang = msgdata.get('lang', mlist.getMemberLanguage(sender))
+        cset = Utils.GetCharSet(lang)
         subject = unicode(subject, cset)
     # and substitute %d in prefix with post_id
     try: